The goal of the proposed work is to develop an early, telephone-based, trauma focused cognitive behavioral therapy intervention (ET-CBT) and evaluate its efficacy in preventing post-traumatic stress disorder (PTSD). PTSD is frequent, disabling and treatment resistant. Current evidence supports the efficacy of face-to-face trauma-focused cognitive behavioral therapy (CBT) in preventing PTSD. The required clinical resources are limited, however, particularly in war, terror or disaster-affected areas. Finding ways to deliver CBT via remote telecommunications is a high priority. Telephone based CBT has been successfully delivered in anxiety and mood disorders. Studies of populations under threat show that telephone support services are widely used. The proposed work will adapt an existing CBT protocol for telephone based delivery, pre- test a preliminary version of the intervention for consistency, feasibility and acceptance; develop an advanced version and evaluate it in a large randomized controlled trial (RCT). Following a preliminary evaluation that established it feasibility, tolerance and potential for beneficial effect, an open-label study will evaluate 20 survivors and establish the intervention's manual. Eminent consultants will participate in designing the intervention and monitoring its implementation. For the RCT, we will screen 1500 survivors of traumatic events, from a general hospital ER trauma registry, randomize the first 200 who have Acute Stress Disorder (ASD) or Acute PTSD to either ET-CBT (n=100) or no-treatment condition (n=100), provide ET-CBT to the former within a month of the traumatic event, and compare the two groups at three months. Survivors with PTSD at three months will receive face-to- face CBT. A second evaluation, at eight months will examine the stability of recovery with ET- CBT and added beneficial effect of in-person CBT in who did not respond to ET-CBT. This proposal is molded on the R34 mechanism entitled Mental Health Consequences of Violence And Trauma (PA PAR-07-315) that encourages the development of new or adapted interventions. It addresses to the Institute of Medicine (IOM) 2007 recommendation to Promote specific research on early intervention in PTSD. The successful development of ET-CBT will contribute to solving a major service-delivery problem and provide a new tool for preventing PTSD. It will enable timely treatment to survivors in war and disaster-affected areas. The proposed interventions can be readily converted to web-based vehicles of voice- and image communication, available to a growing segment of the population.